Electric-circuit tuning device



Apri129,193o. WA READY 1,756,570y

ELECTRIC CIRCUIT TUNING DEVICE Filed Oct. 25, `192?.

which illustrate a preferred/embodiment of Patented Apr. 29, 1930 UNITED STATES PATENToFl-flca WILLIAM A. READY, OF BROOKLINE, MASSACHUSETTS ELECTRIG-CIRUIT TUNING DEVICE Appiication inea october 23, 192e. serial N0. 143,718.

my invention Figure 1 is a cross-section tlOugh/fro and base panels of ai/conventinal radio receiver, showing inYside elevation, a variable 1 air condenser, secured to the panels, a usual and the front panel being omitted;

dial being shown in dotted lines, secured'upon an adjustable shaft made in accordance with my invention;

-Fig. 2 is an end elevation of the condenser, the base panel being shown in cross-section Fig. 3 is a section on the broken line 3-3 of Fig. 2, showing one means for interlocking the plates of the condenser upon the hollow shaft;

F ig;. 4 is an enlarged section on the broken line 4 4 of Fig. l, showing the formation of the hollow shaft;

Figs. 5 and 6 are sectional views, on the broken line 5-5 ofFig. 3, showing respectively a condenser plate before, and after, portions of the material of the plate have been upset to interlock the plate with the hollow shaft;

Fig. 7 is an enlarged sectional detail on4 the broken line 7-7 of Fig. 5; Vand Fig. 8 is an enlarged sectional detail on the broken line 8-8 of Fig. 6.

In the illustrative embodiment of my invention shown in the drawings, I have employed a variable air condenser ofthe type generallyused in connection with the tuning of a radio circuit. The particular type of condenser` illustrated has a set of movable plates l, shown in the upper part of Fig. 1, and a set of stationary plates 2, shown at the lower part of Fig. 1, and in section, Fig. 2, bothsets of plates being supported upon a suitable frame. This frame, as here shown, comprises a base and upright pieces supporting the setsof plates. l

The movable plates 1 are carried by a support, in the form of a hollow shaft 3, jour-y naled in bushings 4, threaded into the frame,

as shown in Figs. l and 3. The bushings 4 lmay be -screwed lin and out of the frame to permit axial adjustment of the group of movableplates 1, in relation to the stationary plates 2, lock nuts 4a holding the bushings in adjusted positions. l The endsv of the hollow VVshaft 3 are frusto-conical and engage internal frusto-conical shaped walls of the bushings to provide a smooth bearing for the set of movable plates 1, as' shown in Fig. 3.

The hollowshaft 3, (Figs. 3 and'4),is provided with two series of uniformly-spaced slits 5, cut into the shaft transverse to the axis' y thereof, and two internal, longitudinal,

grooves 6, parallel lwith and opening into 'theA axis of said shaft. Each groove 6 intersects shown in Figs. 5 and 6. The side walls of or cuts one of the series of'slits 5. Each of,`

the.slot 7, (Fig. 5), are spaced the: same distance apart as the flat edges of the hub 8 sog-1 that, when a plate 1 is slid over'the hub,rthe" plate'is held against turning relative to the shaft 3. All the plates are thereby held in'- ff perfectly spaced alignment. When the plates l are placed upon the hubs 8, portions 9 adjacent the side walls of the slots 7 intersect thebore of the shaft 3, as shown in Figs. 3 and-5, and these portions 9 have notches 10 to assist in centering and guiding a suitable tool through the shaft to upset said portions. The tool when inserted in or drawn through the bore of the shaft 3 presses portions (Figs.`

3, 6 and 8) of each plate, into the grooves 6,

thereby locking the plates so that they cannot slip relative to.. or become accidentally separated from. the shaft 3. The upset portions ll in the grooves 6 also prevent the' plates turning relative to the shaftY 3. The above described method of attaching the plates to their support is simple and eifective, and may be employed to secure-sets' of stationaryl plates.

The frame, see Figs. 1 and 2, includes a pair of upright members 12-12, and lspacing means inthe form of sheet metal strips 13-13. 'The ends of the strips are counter-l A'sunk into the upright pieces 12-12, as shown in Fig. 2, and fit tightly into the grooves 14, cut in opposite sides of the `uprights The frame parts are suitably heldtogether as by the countersunk screws 15, shown in Figs. 1 and 2. lVhen the parts are thus assembled, the frame is substantially as rigid as a onepiece frame. and has the advantages that the strips 13-13 may be made in any suitable length, and the uprights may be spaced to accommodate any given number of plates.

F urthe'rmore, the strips 13-13 may be made long enough to connect several upright pieces, so that two or more condensers may be aligned and the movable plates connected by a single shaft. construction illustrated, three uprights and two connecting pieces may be provided to support two se-ts of condenser plates, whereas in a one-piece frame construction, the use of two complete frames would be required to perform lthe same function. It is easier to assemble and adjust the condenser where the frame is formed of several pieces as illustrated. A

Thecondenser illustrated may be secured directly to the front panel 16 as by screws 17, as shown in Fig. ,1, and the base panel 18 may be supported by-securing it directly to the bottom of the condenser, as by the screws 19..

Heretofore, it has, in many instances, been diiiicult to connect an operating knob or dial to the shaft of an instrument located behind the panel of a radio receiver, because the shaft is, in many instances, either too long or too short when extended through the panel. In such cases the dial cannot be properly secured to the shaft until there has been some alteration, as by adding a sleeve to make the shaft longer, or cutting off a portion of a shaft. To make such changes unnecessary, I. have provided an adjustable shaft 20, of non-conducting material, (Figs. 1 and -This shaft telescopes within the hollow shaft 3, and is guided by the bushings 4, as shown in Fig. 3. One end of the shaft 20 passes through the panel 16, and a tuning knob or dial (shown in dotted lines, Fig. 1) is secured thereto. Thus it is a simple matter'to loosen the set screw 21 and slide the shaft to t the dial and then tighten the set screw. The sliding shaft 2O is also useful when connecting several tuning devicestogether, as a single shaft may pass through a number of hollow shafts and be used to turn all of them.

To prevent interference with smooth sliding action of the shaft 20, relative to the upset portions of the plates,the hollow shaft, adjacent to the slits 5, is provided with a bore 21,u of larger diameter than the diameter of the shaft, so that any slight irregularities, formed when interlockingthe plates, will be spaced from the shaft 20. If desirable, the

bore may be the same diameter as the shaft.

20 providing that the upset portions do not For instance, in the framev project into .the bore from the grooves, or as illustrated in Fig. 3, one end of vthe hollow shaft 3, beyond the plates 1, may be bored to lit the shaft 20, the remainder of the bore being larger in diameter'.

While I have shown, in Fig. l, the stationary plates 2 as being secured together by -means of spacing elements 22, screws 23 and nuts 24, and mounted in brackets 25 secured to the upright pieces 12--12 ofthe frame," these plates may be assembled and secured to the frame in substantially the same manner as the plates 1.

My invention is not restricted to the illustrative embodiment shown and described.

Claims:

1. An electric circuit tuning device having a hollow shaft provided with a slit, a tuning plate member carried by said shaft and plate fastening means integral with ,Said plate member, Vsaid plate fastening an intermediate hub portion provided by r said shaft between said slits to support said plate' and prevent relative turning thereof and interlocking means integral with said plate and formed by upsetting portions of said plate against the wall of the bore of said shaft to prevent accidental separation of the plate from the shaft. i

3. An electric circuit tuning device comprising a hollow shaft, a set of plates carried by said shaft, a plurality of rows ofslits formed in said shaft and terminating inV spaced relation to provide between them hub means for cooperation with the plates to prevent turning thereof relative to the shaft, longitudinal grooves formed in the wall of the bore of said shaft and intersecting said slits and plate fastening rivet means integral with said plates and having portions thereof upset and pressed into said longitudinal grooves to provide means for locking the plates to the shaft.

1. A tuning device for radio receivers comprising a hollow shaft, andits support,.said shaft having a plurality of spaced slits intersecting the bore thereof, plates assembled in said slits and having rivet means intersectingv said bore, said sha-ft having a groove into which the intersecting portions of the rivet means are pressed and upset to secure the plates upon said shaft.

5. An electric circuit tuning device having a frame, said frame including relatively narrow posts having grooves formed in the sides thereofA adjacent to their lower ends, a

pair of connecting bars lfitted into saidv grooves so as to be countersunk into said posts to resist torsional stresses and contribute rigidity to the frame, fastening means removably fastening said1 connecting bars to c said posts and tuning means Ysupported by means attached directly/to said posts independently of said connecting bars.-

6. An electric circuit tuning device comprising, in combination, a iframe, said frame having a pair of end-pieces, circuit vtuning means supported between and by said end ieces a air of s aced connectin ieces of desired length independent `of t e circuit tuning means, fastening means removably v securing .said connecting pieces to said end pieces and .said connecting pieces and said end pieces being countersunk at opposite edges of the end pieces the'one with the other to resist torsional stresses and contribute ri id ity to the device;

An electric circuit tuning device having a frame comprising. a plurality of' relatively narrow upright members, tuning means supported between Vsaid upright members and detachable spacing means secured to said uprightmembers, fastening means detachably securingsaid spacing means to said upright members independently of said tuning means for spacing said vupright. members whereby the space between two uprightl membersis governed according to the length of the spacing means used. v

In testimony whereof, I have signed my name to this specification. f

WILLIAMVA. READY. 

